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Auto Range Mode
Thermo Fisher Scientific
Table 3-3. Default Analog Outputs in Dual Range Mode
Channel
Pin
1
14
2
33
3
15
4
34
5
17
6
36
Ground
16, 18, 19, 35, 37
Note All channels are user definable. If any customization has been made to
the analog output configuration, the default selections may not apply.
The auto range mode switches the O
ranges, depending on the concentration level. The high and low ranges are
defined in the Range menu.
For example, suppose the low range is set to 500 ppb and the high range is
set to 1000 ppb (Figure 3-6). Sample concentrations below 500 ppb are
presented to the low ranges analog output and sample concentrations above
500 ppb are presented to the high ranges analog outputs. When the low
range is active, the status output is at 0 volts. When the high range is active,
the status output is at half of full-scale.
When the high range is active, the concentration must drop to 85% of the
low O
range for the low range to become active.
3
In addition, each O
analog output has a span coefficient. There are two
3
span coefficients so that each range can be calibrated separately. This is
necessary if the two ranges are not close to one another. For example, if the
low O
range is set to 0–50 ppb and the high O
3
ppb.
I/O Terminal Pin
Description
1
O
Low Range
3
3
O
High Range
3
5
None
7
None
9
None
11
None
2, 4, 6, 8, 10, 12
Signal Ground
analog outputs between high and low
3
range is set to 0–20,000
3
Model 49i Instruction Manual
Operation
Range Menu
3-11
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Troubleshooting
